More than 200 veterinary ophthalmologists across the United States -- and four clinics in Washington -- are doing free eye exams on service animals this spring.

The event --the American College of Veterinary Ophthalmologists' 5th annual ACVO/Merial National Service Dog Eye Exam event -- runs through May.

People who have a service dog, ­­­­­ including handicapped assistance dogs, detection dogs and search and rescue dogs, can register for the free event online from April 1 through April 30. Since the event's inception in 2008, more than 10,500 service animals -- including some horses and a donkey -- have been examined.

People can register a service animal for the event online at ACVOeyeexam.org.

The Washington State clinics participating are:

-- Northwest Animal Eye Specialists in Kirkland
-- Washington State University in Pullman
-- Animal Eye Clinic in Seattle
-- Animal Eye Clinic of Spokane in Spokane